1. Field of the Invention
The present invention relates to a golf putter, and more particularly to a golf putter capable of being swung in an accurate direction while having a face forming an accurate angle with a golf ball when a golfer strikes the golf ball on a green.
2. Description of the Related Art
A putter is a club used for golf and is used for the purpose of putting a golf ball into a hole by striking the golf ball placed on a green. In golf, the most important elements are accurate directional properties and force regulation.
In this case, a golfer should sensuously putt the golf ball by grasping characteristics such as a distance and line between the golf ball and a hole such that the golf ball rolls on the lawn of the green as if a wheel rolls. Thus, the golf ball is less affected by slight variations in the green surface.
When the putter impacts the ball, a head of the putter is preferably adapted to be square relative to a movement direction of the ball. The putter adapted to be square has to impact the ball such that a so-called sweet spot of the putter passes a center of the ball.
In putters developed to improve putting skill of golfers, a putter known to have heel-toe balance in which an engineering principle is introduced to the putter has been developed. Before such a development, most of putters were blade putters having a flat plate shape. In brief, in a putter designed according to a heel-toe balance principle, a heel and toe of a putter head have mass bodies. This enables the putter head to have an increased moment of inertia such that the putter may resist torsion generated when the golf ball is struck at a putter face point spaced apart from the sweet spot of the putter. The putter keeping the heel-toe balance has face balance which is another manufacturing characteristic. The putter having the face balance has the same one moment arm. This means that the mass bodies at the heel and the toe are located at the same distance from a rotary axis. This is configured by connecting a shaft of the putter to a center between the toe and the heel of the putter, namely, by connecting the shaft to be close to a center of gravity. U.S. Pat. No. 3,954,265 discloses a putter keeping face balance by another method. In this case, a shaft is attached to a putter head at a position close to a heel and is bent in a specific shape. A bent portion at the shaft is located at a lower end portion thereof.
As shown in FIGS. 1 and 2, a putter 10 includes a putter head 12 having a typical face 14 with which a golf ball is struck, a toe 16, and a heel 18. The putter 10 includes a hosel 20 having a specific shape to be described in detail later. Although not described in detail, it will be understood by one skilled in the art that a long shaft 22 has a lower end portion which is tightly fixed to an upper end portion of the hosel 20, the shaft 22 defines a vertical axis 24, and a typical grip 2 is mounted to an upper end of the shaft 22.
As is well known, every object has a center of gravity regarded as overall weight of the object being concentrated on one point. A center of gravity of the putter head 12 is indicated by a point CG. An imaginary line 26 perpendicular to the face 14 of the putter head 12 passes through the point CG and a spot 28 on the face 14 of the putter head. The spot 28 is a sweet spot of a golf club known in the art. When a swing path of the golf club, namely the putter 10 coincides with the imaginary line 26, the golf ball is impacted on the sweet spot 28 to generate maximum energy transfer, with the consequence that torsional force is not applied to the putter head. If the golf ball is impacted at a position away from the sweet spot 28, force of rotating the head about the vertical axis 24 of the shaft 22 is applied to the putter head 12. This undesired rotation of the putter head 12 may be restricted by inertia and the putter 10 has a shape for maximizing a moment of inertia.
As shown in FIG. 2, the putter head 12 includes a first mass concentration portion M1 at the toe 16 of the putter head 12 and a second mass concentration portion M2 at the heel 18 of the putter head. The moment of inertia of the object about any axis is defined by summing values obtained by multiplying the square of a distance from the axis and each mass. As in the putter 10, the heel-toe balance means that the concentration portions are located at the toe and the heel.
Another method of improving stability of the putter is face balance known in the art. The face balance is generated when each of the mass concentration portions M1 and M2 are located at the same distance from the vertical axis 24 of the shaft 22. The stability of the putter may be further improved when a distance from each axis of the mass concentration portions M1 and M2 is maximized within a possible range. The above objects are accomplished by the provision of the above-mentioned hosel 20 having a specific shape.
Referring to FIG. 1, the hosel 20 extends from a position close to the heel 18 of the putter head 12. The hosel 20 includes a vertical leg portion 30 having a bent upper end portion to form a cantilever arm 32 extending forward of the putter head 12. A socket protrusion portion 34 is formed at an extension end portion of the cantilever arm 32 and the lower end portion of the putter shaft 22 is fixed into the protrusion portion 34 as described above. The vertical leg portion 30 of the hosel 20 has a length determined such that the vertical axis 24 of the putter shaft 22 intersects the imaginary line 26 at a point 36. Accordingly, by the above-mentioned hosel 20 having a specific shape, the vertical axis 24 of the shaft 22 is located such that distances between the mass bodies M1 and M2 and the axis 24 indicated by respective imaginary lines 38 and 40 are equal to each other, and the putter will rotate about the axis 24 when the putter is struck at a position away from the spot. Particularly, the distances, which are caused by offsetting the intersection point 36 forward of the putter head 12 and are indicated by the imaginary lines 38 and 40, are maximized within an actual range. The stability of the putter head is achieved by forward location of the intersection point 36. Since the center of gravity CG is a point at which overall weight of the club head 12 is concentrated, the center of gravity CG will act as a mass concentration point.
The mass concentration portion cooperates with the distance between the center of gravity CG and the intersection point 36 and generates another moment of inertia for restricting torsion of the putter 10 due to striking of the putter at a position away from the spot.
However, in every case, the shaft 22 is obliquely coupled to the conventional putter 10 instead of being perpendicular to the ground. Thus, it may be possible to prevent movement (bending) of the wrist during a stroke (a stroke action of the ball) and to naturally send the ball to a target point by linking rotation motion of the spine to linear motion of the arm.
FIGS. 3 to 5 show that a golfer addresses the ball with the club in a state of taking a stance. During address of the ball, a known desirable posture is that, when the golfer looks down on the ball in a state in which the club head is parallel with the ground, a viewing line 7 joining the golfer's eye to the golf ball 6 is perpendicular to the ground, as shown in FIG. 4. The viewing line 7 as shown in FIG. 4 is away from the vertical state when the golfer's eye is located behind the golf ball 6 as shown in FIG. 3 or the golfer's eye is located in the front of the golf ball 6 as shown in FIG. 5. For this reason, when the ball is struck with such a posture, the ball is away from a target direction. The putter 10 has a defect which may not ascertain whether or not the viewing line 7 is vertical even though the putter head 12 is parallel with the ground. In other words, since it may not accurately ascertain whether the golfer's own eye is located in the front of the ball or behind the ball, the golfer performs putting depending upon a sensory feeling.
Golf is often referred to as a metal game. Uncertainty about golfer's own determination of whether the putter located at the ball accurately corresponds to the golfer's eye viewing the same during putting address of the ball will more increase stress of the golfer during putting on the green.
Accordingly, putters for accurately striking the ball by various methods, such as using a putter head provided with an indication line to ascertain an accurate direction or using a putter head provided with a leveler, have been developed. Korean Patent No. 10-1276686 filed by the present inventor discloses a putter for informing a golfer of a swing direction of a putter head. Hereinafter, the putter will be described.
As shown in FIG. 6, a conventional putter 50 includes a putter head 51 which has a plurality of horizontal protrusions 51a formed on a face surface for striking a golf ball at a sweet spot, an arc-shaped neck 52 which is formed on a radial line of curvature of a central point of the putter head 51, is spaced apart from an upper surface of a toe 51b as a front portion of the putter head 51, and is integrally connected to a heel 51c as a rear portion of the putter head 51, and a hosel 53 which is integrally formed with the neck 52 to insert a putter shaft 22 gripped by a golfer's hand and is configured such that a lower end extension line of the putter shaft 22 is directed toward the central point of the putter head 51 while being inclined toward a golfer's body with respect to a vertical line.
Accordingly, a line CGL passing a center of gravity of the putter head 12 is naturally located at the center of the putter head 12. The center line of gravity is indicated by reference numeral CGL and coincides with a swing line during putting.
When a swing path of the putter 50 coincides with the center line of gravity CGL, the golf ball is impacted on the sweet spot to generate maximum energy transfer, with the consequence that torsional force is not applied to the putter head. If the golf ball is impacted at a position away from the sweet spot, force of rotating the head about the hosel 53 is applied to the putter head 51. This undesired rotation of the putter head 51 may be restricted by inertia and the putter 50 has a shape for maximizing a moment of inertia.
The neck 52 extends forward of the hosel 53. Therefore, force, namely, kinetic energy generated by swing of the putter head 51 toward the heel 51c or the toe 51b during impact of the putter is distributed so that the putter head 51 is prevented from rotating.
In addition, the neck 52 has a neck groove 52a formed on an upper surface of the neck 52 coinciding with the vertical line of the central point of the putter head 51. The putter head 51 has a putter head groove 51d formed in a linear shape so as to coincide with the center line of gravity CGL as the swing line of the putter head 51 at a symmetric center between the heel 51c as the rear portion and the toe 51b as the front portions of the putter head 51.
As such, by forming the linear-shaped neck groove 52a and putter head groove 51d coinciding with the swing line of the putter head 51, the golfer putts the ball after visually ascertaining whether the two linear-shaped grooves 52a and 51d coincide with each other by the golfer's own eye during putting. When the two grooves do not coincide with each other, the golfer putts the ball in a state in which the putter head 51 is inclined in a forward and backward direction of the golfer with respect to the ground. Thus, the golfer may not send the ball along a desired putting line.
Here, the putter serves to prevent the putter head 51 from being putted in a state in which the putter head 51 is inclined in the forward and backward direction of the golfer with respect to the ground. However, the putter may not check a state in which the putter head 51 is inclined in the forward and backward direction of the golfer.